Bridge



Feb. 11.1925.

R. G. MICHIE BRIDGE F 11ed Oct. 11, 22 Sheets-Sheet 1 l I mvguroa W6. MIC HIE;

85 A TTORNE Y8 Feb. 17, 1925.

R. G. MICHIE BRIDGE Filed on. 11. 1922 3 sneets-shet a INYEIVTOR 7P6. Mic/we mom/us WITNESSES Patented Feb. 17, 1925.

ROY GILES MICI-IIE, F MO'NTE'VIDEO, MINNESOTA.

BRIDGE.

Application filed October 11, 1922.

To all whom it may concern:

Be it known that I, ROY GILns Mionrn,

a citizen of the United States, and a resident of Montevideo, in the county of Chippewaand State of Minnesota, have invented certain new and useful Improvements in Bridges, of which the following is a specification.

My invention relates to improvements in bridges for open ditch crossings and it consists of the constructions, combinations and .mode of assembly herein described and claimed.

An object of the invention is to provide a bridge which is intended for use at places where highways cross open ditches or creek beds, requiring frequent dredging, a feature of the bridge being that the bridge deck can readily be removed so that the dredging implement may readily pass through to reach the bottom of the ditch or creek.

Another object of the invention is to provide a bridge in which the deck is made in sections or slabs which embody means by whichthey can readily be removed and by which they can as readily be replaced as they were in the original structure.

Other objects andadvantages will appear in the following specification, reference being had to the accompanying drawings, in which: i

Fig. 1 is a perspective view of a bridge constructed in accordance with the invention, two of the slabs being shown omitted for the purpose of illustrating the longitudinal girders and also of showing the transverse tie rod, I

Fig. 2 is a cross section of Fig. 1,

Fig. 8 is a detail perspective view of a portion of one end of the bridge, showing how the longitudinal girders are fastened to one of the end abutment plates.

Fig. 4c is a. detail perspective View of a portion of the central part of the bridge, more clearly illustrating how the tie rod is attached to one of the railing standards,

Fig. ,5 is a side elevation of a portion of the railing and bridge structure again showing how the standard is assembled onthe outside longitudinal girder,

Fig. 6 is a plan view of one of the deck sections or slabs, illustrating the reenforcing scheme in dotted lines,

on the line 2-2 Serial No. 593,783.

Fig. 7 is a longitudinal section of the slab in Fig. Gagain showing the arrangement of reen'lt'orcing rods,

Fig. 8 is a detail perspective view of one end of one of the slabs, and

Fig. 9 is a detail cross sectional view showing how the slightly beveled ends of the slabs aid in laying them.

In carrying out the invention, provision is made of a plurality of I-beams or girders 1 which are laid across the ditch or creek D (Fig. 1) and consequently extend longitudinally oi the passageway of the bridge. The girders are spaced equal distances apart, and in order to hold them so, spacer plates 2 are provided at each end, these having angle irons 3 bolted or riveted thereto in pairs so as to form narrow 0pen ings to receive the ends of the webs of the girders.

The spacer plates 2 are suitably disposed upon the end abutments 4 and as the ends of the girders 1 also rest upon these abutments, it is obvious that the angle irons 3 merely hold the girders in spaced relationship and exercise no supporting function for the bridge. The abutments 4 are usually built of concrete and are located at places where the roadway (Fig. 1) meets the ditch. The length of the girders 1 must naturally vary with the distance from side to side of the ditch, the ordinary run of ditches approximately being from 17 to 30 feet wide. The span of the bridge must therefore be regulated in accordance with the distance bet-ween the abutments, and in all ordinary spans the design of the bridge will approximately be as illustrated in the drawings.

A. plurality of sections or slabs 5 form the deck or floor of the bridge. Each of these has a curb section 6, which sections when fitted together, form curbs which run longitudinally of the bridge as in Fig. 1. The slabs 5 may be made of any suitable material but a construction of concrete is contemplated at present. lVhen making the slabs of concrete, it is necesary to employ a suitable arrangement of reenforcing; rods 8 which run not only longitudinally, but also transversely, as indicated in Figs. 6 and 7.

While it is of no particular importance; to give dimensions, etc., in this application,

it is regarded of interest to say that the concrete slabs 5 weigh about one ton each. They fit crosswise of the bridge and rest on the girders 1, each slab covering one-half the width of the bridge and covering approximately 3 feet of the length. Each slab has a plurality of lugs 7 which protrude on the underside and are located at such places that they engage the two central girders 1 (Fig. 2) and the outside girders. It is this engagement supplemented by the weight of the slabs that adequately holds them in place.

Provision is made of rings 9 to enable lifting the slabs from the girders when it it desired to have access to the bed of the ditch. These rings are carried by hooks 10 which have bent ends 1.1 to more firmly hold the hooks in their embedded position in the cone ete slabs. The upperends of the hooks and the ringsoccupy circular recesses 12 so as to bring the rings flush with, or a little below, the surface of the slabs.

Attention is directed to Fig. 9 which, although not so indicated, is a section taken longitudinally of a portion of the bridge in Fig. 1. Each of the slabs 5 is shown as being slightly beveled at 13 along one of the long edges which runs transversely of the bridge. The purpose of this beveled edge is to facilitate laying the slabs. In laying the slabs (see the slab 5 being put in position) the beveled edge 13 will be brought into contact with the straight edge of the slab already laid. As the beveled edge traverses the adjacent straight edge, a wedging action will occur, causing the diametrically opposite corner of the slab to slide along the tops of the girders and so find its proper position, incidentally causing the seam between the two slabs to be very fine and close.

Situated inthe center of the bridge and extending transversely of the girders 1 a tie rod 14. (Figs. 1, 2 and t) the ends of which are threaded and passed through suitable holes in the adjacent standard 15 of the bridge railing 16. Nuts 17 are applied to the threaded ends of the tie rods and serve the purpose of keeping the bridge girders from spreading transversely.

The slabs 5 in the center of the bridge have quarter-round recesses 18 (Figs. 1 and 8) to fit over and receive the tie rods 14.

The standards 15 of the bridge railing are riveted or otherwise secured at 19 to angle bars 20 which in turn are suitably secured at 21 to the outermost longitudinal girders. Although the bridge herein dis closed is described and shown as having only one transverse tie rod 14, it is evident that more of these tie rods may be provided depending on the length of the span.

lVhile the construction and arrangement of the improved bridge as herein described and claimed, is that of a generally preferred form, obviously modifications and changes may be made without departing from the spirit of the invention or the scope of the claims.

I claim 1. A bridge comprising a supporting structure, composed of a plurality of parallel girders, a deck consisting of slabs laid in pairs transversely of the bridge throughout the span thereof, each slab resting on a plurality of girders but having no other connection therewith; and lugs protruding from the underside of each slab adjacent to each end to engage the outermost and central pair of girders to hold the slabs in position upon said structure.

2. A bridge comprising a supporting structure, a deck composed of a plurality of slabs adapted to be laid in pairs transversely, each having a curb section on the outer end said sections being adapted to form a. curb lengthwise of the bridge when all slabs are fitted in place, lugs embedded both in the curb sections and inner ends of each slab and extending down to fit against portions of the structure and hold the slabs in position, and means carried by the slabs enabling lifting them off and replacing them into the former position.

3. A bridge comprising a plurality of parallel members extending along the span and forming the supporting structure,

abutments upon which the ends of said members rest, means associated with the abutments to keep the members in spaced rela tionship, a transverse tie rod, means upon the outermost longitudinal members to which the ends of the tie rod are secured,

'and a'plurality of removable and replaceable slabs laid upon the supporting structure to form the deckof the bridge, each slab having means to engage certain ones .of the longitudinal members and thus hold them in position, the slabs next to the tie rod having recesses along certain edges to house the tie rod.

4:. A bridge comprising a supporting structure composed of a plurality of parallel members extending longitudinally of the-span, abutments upon which the ends of said members rest, means associated with the abutments keeping said members in spaced relationship, railings along the side of the bridge including standards, means through which the standards are secured to the outermost longitudinal members, a tie rod extending transversely of the bridge and having connection at the ends to certain of the railing standards, a deck composed of removable and replaceable slabs. means carried by the slabs to engage certain'ones of the members when laid in place to thereby hold them in position, the slabs coming next to the tie rod having recesses along certain edges to receive and house the tie rod; and means embodied in each of the slabs by which they may be lifted for removal and replacement.

A separable bridge comprising a plurality of permanent girders, railing standards erected on the outermost "girders in transverse alinement, a tie rod extending across the girders from one standard to the other, and deck slabs removably laid on the girders the slabs next to the tie rod 

